Well, I think that in Japanese メリークリスマス is far more common (and more correct), however some people I have met tend to use “Happy Christmas” when speaking to foreigners.

There are also differences in saying thanksgiving->
勤労感謝の日(kinro kansha no hi) is the Japanese form of Thanksgiving (similar to our labor day I guess). And, 感謝祭 (kansha sai) is the American form of thanksgiving (eating turkeys, etc.).

The difference in the kanji is a festival for thanks in the latter, whereas the former indicates just a day of giving gratitude and thanks.

Thank you for your comment. Yes, of course “Merry Christmas” (メリークリスマス) is more common, which is why I feature it. However, some Brits (I’m an American) insist on “Happy Christmas” and want(ed) to know how to write it in Japanese (i.e., in katakana), thus I accommodated them.

That’s interesting, what you say about “感謝祭”. I’ve never heard that before. As The-Last-Thursday-in-November Thanksgiving celebrating the Pilgrims and such is a uniquely American holiday (not talking about a day or festival to generally give thanks . . . which is found in most every culture, of course), then I’ve only heard my Japanese friends and colleagues say, “Happy Thanksgiving” referring to that. It’s like if an English speaker asks “How do you say ‘sumo’ in English?” or “How do you say ‘kabuki’ in English?” — sumo is sumo, kabuki is kabuki, and, “Happy Thanksgiving”, 日本語で, is ハッピーサンクスギビング.

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